The present invention relates to a programming device for a stored-program controller.
In modern [closed-loop and open-loop] control technology, a programming device for a stored-program controller is generally understood to mean a small data processing system which is of compact construction and therefore easily transportable and which can be connected via a standardized interface to a large number of different controllers. In the programming device, all the functions which are necessary for generating and maintaining the control programs for the stored-program controllers are combined. For this reason, the corresponding functions do not need to be provided in the controllers themselves. To facilitate the programming work for the control technician, programming devices allow programming to be carried out directly at the function diagram level, that is in a representation which is particularly familiar to the control technician. For this purpose, the function diagram of the respective controller is represented on a graphic display device of the programming device and the user can carry out changes or additions to the function diagram by means of simple commands. The control program associated with the function diagram is automatically generated by the programming device without intervention by the user. Conversely, the programming device automatically generates the associated function diagram on the display device from an already existing machine-readable stored control program.
A programming device of the type described is known, for example, from a book by Hans Berger, published by Siemens Aktiengesellschaft, Berlin and Munich, having the title "Steuerungen programmieren mit STEP 5" ["Programming controllers with STEP 5"], volume 1, 4th edition, 1984. Even in the known programming device, the user can generate the control program for the stored-program controller directly in the function diagram. However, the known programming device operates with a function-diagram representation of greatly restricted generality in which the individual function blocks are exclusively hierarchically linked to each other and in which, therefore, no signal branchings and signal intersections can occur. If, for example, one and the same signal is needed as an input signal by two function blocks, which is frequently the case, the known progamming device generates two separate part-function diagrams on the display device in order to avoid signal branchings in the function diagram. This detracts from the clarity and the information density of the picture shown. But clarity and information density of the picture shown are decisive factors in the handling and in the ease of operating the programming device. Since the profitability of program generation and program maintenance, and thus the efficient processing of the automation tasks overall increasingly depends on simple handling and great ease of operation, the generation of function diagram representations with higher information density is urgently required.
In general, however, the generation of function diagram representations of more complicated configurations is associated with a higher computing effort for the digital computer. Its computing power and storage capacity, however, cannot be easily increased without concessions in size, weight and price.
The present invention achieves the object of providing in a programming device of the type initially mentioned operations in the operating system of the digital computer by means of which the function blocks in the function diagram representations are efficiently automatically arranged in such a manner that signal branchings and signal intersections can also be represented between them.
The advantages achieved by the invention can be essentially seen in the fact that the success aimed for, that is to say the automatic generation of function diagram representations including signal branchings and signal intersections, and therefore high information density, is achieved in a particularly efficient manner. No increase in computing power and in the storage capacity of the digital computer is required.